The person says Barra's appearance has been cleared by GM and is awaiting final approval from the university. The Associated Press left a telephone message with the university Wednesday afternoon seeking comment. The Detroit News reported Barra's expected appearance Wednesday morning. The spring commencement takes place May 3rd at Michigan Stadium. The 52-year-old Barra took the top job at GM on January 15th after chief executive Dan Akerson stepped down to help his wife battle cancer.